Conventionally, underwater detection devices which detect underwater by transmitting ultrasonic waves underwater and analyzing echo signals which are reflections caused by the ultrasonic waves are known. Such an underwater detection device generates and displays a detection image indicating signal levels of the echo signals corresponding to a water depth and placed in a chronological order (an order of acquisition of the echo signals).
JP2001-092576A discloses a depth sounding device provided with a plurality of switches at a right side of a display screen. A menu screen is displayed by controlling the switches. The menu screen is displayed in a large size at a center of a detection image. Further, JP1990-124492A discloses a fish finder which displays a menu screen below a detection image.
However, with JP2001-092576A, since the large menu screen is displayed at the center of the detection image, the detection image is uneasy to confirm while the menu screen is displayed. With JP1990-124492A, although the detection image is not blocked by the menu screen, since the menu screen dominates a part of the screen area, a situation arises that the detection image becomes small.